Cycling UK Forum

pete75 wrote:

TonyR wrote:

pete75 wrote:Yep - simple really. It was Germans who put the men on the moon - the yanks just financed it. It all stemmed from something called operation paperclip in which the USA grabbed over a hundred rocket scientists from Germany at the end of the war.

On that basis the Americans haven't done anything aside from perhaps some stuff done by native Americans. Apple's Syrian, Facebook is Israeli and the country is run by a Kenyan.

But Jobs was born and brought up in the USA as was Zuckerberg - Judaism is a religion not a nationality. You're obviously one of those birthers if you don't think Obama isn't a born and bred American.

I'm sure that was a joke, but he has a point. The USA was built on the backs of its immigrants. It is an immigrant nation, and even when I was child, people asked each other 'where are you from', to ask what country someone's family came from. They were immigrants, not Germans. The same thing happens today in many countries when they give people visas because they have specialist skills or knowledge

According to the US National Venture Capital Association, immigrants have started 25 percent of public U.S. companies that were backed by venture capital investors. This list includes Google, eBay, Yahoo!, Sun Microsystems, and Intel.

Using your logic, the Morris Minor and the Mini are Turkish (or maybe Greek), not British because the designer, Sir Alec Issigonis, was born in the Greek community of Smyrna (now Izmir) in Turkey.

Vorpal wrote:I'm sure that was a joke, but he has a point. The USA was built on the backs of its immigrants. It is an immigrant nation, and even when I was child, people asked each other 'where are you from', to ask what country someone's family came from. They were immigrants, not Germans. The same thing happens today in many countries when they give people visas because they have specialist skills or knowledge

According to the US National Venture Capital Association, immigrants have started 25 percent of public U.S. companies that were backed by venture capital investors. This list includes Google, eBay, Yahoo!, Sun Microsystems, and Intel.

Using your logic, the Morris Minor and the Mini are Turkish (or maybe Greek), not British because the designer, Sir Alec Issigonis, was born in the Greek community of Smyrna (now Izmir) in Turkey.

You're absolutely right about the mini designer except that his father was British and Issigonis had British nationality from birth, though his mother was German.

There's a deal of difference between immigrants and people who are more or less forcibly taken from one country to another to work on military and allied technology as were the German rocket scientists.
Must admit what I said about Germans putting the men on the moon was meant as a joke but thinking on there's a great deal of truth in it.

Manc33 wrote:Meanwhile other scientists are debunking the findings and saying that the people claiming the victory are just after grant money - which sounds a lot more like what humans would do (even in science).

Science is corrupted, as fantastic as that might sound.

At one time you used your own senses and that was science in its purest form (and it still is) but those days are long gone. Now you're told everything by "experts" with their "theoretical" this and "theoretical" that.

Any of the anti-science brigade who genuinely believe what they peddle are at liberty to reject science and go and live like mediaeval peasant farmers if they want to. The reason that they don't, by and large, is that they know damned well which side their bread is buttered on.

Not reported that a Gamma-ray burst from the same place as the gravitation waves came from was detected 0.4 secs after the gravitational waves were detected.

Which is where it gets really interesting because for a gamma ray burst you need some matter around your black holes. But is these two black holes had been orbiting each other for a fair time (as has been suggested) they would have cleared out all the matter so when the collide, no matter and no gamma ray burst. So theory that the two black holes might have been created from a very very massive star that was spinning really fast when it collapsed. Then the two black holes would have started off pretty close and they would be plenty of mater around for the gamma ray burst.

But it is possible that the gamma ray burst did not come from the colliding black holes (unlikely but possible).

But then, whilst NASA detected the gamma ray burst, ESA didn't so was there even a gamma ray burst ?

http://www.universetoday.com/127463/did-a-gamma-ray-burst-accompany-ligos-gravitational-wave-detection/

Ian

I wonder....

Could the merger or two black holes create a gravitational wave that matter could 'surf' out of the event horizon? (Completely idle speculation, I've not looked anywhere near the physics of this)
Or could the wave cause issues in localish matter??

[XAP]Bob wrote:I wonder....

Could the merger or two black holes create a gravitational wave that matter could 'surf' out of the event horizon? (Completely idle speculation, I've not looked anywhere near the physics of this)
Or could the wave cause issues in localish matter??

Its possible but not through surfing a gravitaional wave. If a black hole is rotating fast enough it could in theory become what is known as a naked singularity in which the singularity at the centre of the black hole is not shielded from the universe by an event horizon. There has been speculation that a naked singularity could, unlike a black hole, emit light. Its just possible I suppose that as the black holes rotate around each other faster and faster as they come closer together and the event horizons merge, all sort of things could be going on.

Yes the 'collapsing star dividing into two black holes' is an interesting theory - but the merger of black holes has to be sone of those 'edge cases' in physics....

I'd have to re-learn all my GR (which is probably now beyond me, at my age - I've just, in a fit of insanity, downloaded a textbook to my kindle but probably wasted my money) before I can make any meaningful observation on all this difficult stuff.

I also think all the off-topic (and questionable) content ought to be removed from this thread.

My GR was never good enough - my real ability in physics was always classical, and this really isn't

I can cope with stuff with classical analogy, but.... That only gets you so far

All I can remember is, that when you cross the event horizon, spacelike and timelike vectors sort of get 'swapped over'. And the metric is singular at the horizon itself. That's not much to go on. The author of the textbook which I browsed through, when I was a student (GR wasn't actually on the course, I was doing some background reading) blithely pronounced something like "no need to worry, because the event horizon can never occur in reality, it''s always inside the massive body".

Of course, this was in the days before Stephen Hawking burst in upon the scene....

Thinking about this (without understanding), Einstein and/or others have talked about (super)massive objects causing gravitational waves but I've not seen much comment n the (super)massive aspect.

And thinking, I can't see why there should be some mass threshold for the creation of gravitational waves. I would have expected smaller objects to create smaller gravitational waves. So those people playing table tennis, their little ball will be creating very small gravitational waves (probably far too small to ever be detected but moving mass ...). Planets orbiting a star, stars orbiting the galactic centre, galaxies moving through space, galaxy clusters ... I would have guessed it's a matter of how strong those gravitational waves are (and maybe their frequency as well?).

Is there something special about (super)massive objects in relation to gravitational waves or just a question of amplitude and frequency ?

Ian

Psamathe wrote:Is there something special about (super)massive objects in relation to gravitational waves or just a question of amplitude and frequency ?

There's no mass threshold, just that you've no chance at all of detecting something that isn't massive.

As I understand it frequency and amplitude have little to do with the wave itself and everything to do with modulation. The fact that we have two black holes spiralling in towards each other is what modulates the waves. The amplitude is a function of their mass and frequency due to their rotation around each other.

An interesting podcast discussing some theoretical research that might be questioning General Relativity - not that it is wrong (just as Newton is not "wrong"). Discusses the possibility of naked singularities and cosmic censorship and surprisingly I found it understandable'ish.

It starts close enough to the start of the podcast https://audioboom.com/boos/4221795-space-time-with-stuart-gary-series-19-ep-6-biggest-known-black-hole-discovered-plus-more (starts discussing the largest black hole ever discovered and soon moved on to the more theoretical stuff).

Ian

Psamathe wrote:An interesting podcast discussing some theoretical research that might be questioning General Relativity - not that it is wrong (just as Newton is not "wrong"). Discusses the possibility of naked singularities and cosmic censorship and surprisingly I found it understandable'ish.

It starts close enough to the start of the podcast https://audioboom.com/boos/4221795-space-time-with-stuart-gary-series-19-ep-6-biggest-known-black-hole-discovered-plus-more (starts discussing the largest black hole ever discovered and soon moved on to the more theoretical stuff).

Ian

Naked singularities have been known as a theoretical concept for decades. You just need a rotating black hole to get one. And for decades theorists have not known how to deal with the theory of a point that is infinitely small and infinitely dense because the laws of physics as we know them (or rather their mathematics) break down under those conditions.

TonyR wrote:Naked singularities have been known as a theoretical concept for decades. You just need a rotating black hole to get one. And for decades theorists have not known how to deal with the theory of a point that is infinitely small and infinitely dense because the laws of physics as we know them (or rather their mathematics) break down under those conditions.

I haven't had chance to listen to the podcast yet but my (very limited) understanding is that singularities can't really exist since from our perspective matter falling into a black hole will never have reached the centre due to time dilation.

Another thing I was reading a few weeks ago was that there may well be a limit to how dense matter can get. Singularities assume that matter can compress infinitely but there's no evidence that this is true (and in fact black holes could in theory 'explode'!)
Since the issues with singularities are all to do with the theoretical notion that matter can exist as a singularity then if it turned out not to be true then the issues we were having no longer exist.